The invention relates to services provided by an intelligent network and particularly to services provided on the terminating side of an intelligent network call.
A subscriber to a telecommunication network —a wired network or a mobile telephone network —can be provided with a variety of different services by the Intelligent Network (IN). The use of the Intelligent Network is based on call control and on the fact that the normal switching exchange connection arrangements and service control are separated from one another. ITU-T (International Telecommunications Union-Telecommunication Standardization sector) recommendation Q 1214 (10/95) describes a call setup arrangement, according to which exchanges supporting IN services comprise a basic call manager BCM. The basic call manager controls the basic call and the connection for providing the user with communication paths and interconnects these paths. BCM detects the events that can lead to invoking an IN service or that should be reported to an active IN service logic instance. The basic call manager BCM comprises a call-specific state model instance, a so-called basic call state model BCSM, which represents various phases of the call control and includes points where the call control can be interrupted in order to invoke an IN service. Additionally, BCM manages the use of exchange resources.
The IN call setup is divided into two sections: originating-side call setup and terminating-side call setup. The sections can also be called half-calls or call controls. The originating-side call control is associated with the services of a calling party, i.e subscriber A, and the terminating-side call control is associated with the services of a called party, i.e. subscriber B. The originating-side call control is modelled with an originating basic call state model O_BCSM and the terminating-side call control is modelled with a terminating basic call state model T_BCSM. The terminating basic call state model is invoked when the originating basic call state model reaches a point in routing, in which a routing address and call type are interpreted and the next route is selected. Thereafter, the originating basic call manager sends information on the call attempt to the terminating basic call manager to be further processed by a setup message. Upon receiving the message, the terminating basic call manager invokes the terminating basic call state model. These basic call state models interchange information by indications, but in the routing phase and while the call is active, the originating basic call state model does not send the terminating basic call state model other than the indication that a call has been attempted, which invokes the terminating basic call state model.
Interaction-points, so-called detection points, are determined in the basic call state models, where event handling is either interrupted, information is sent to the IN service control function and instructions are awaited from the IN control function, or alternatively, only a notification of what has happened is sent to the IN service control function. An IN service is provided such that when encountering service-related detection points, instructions are asked from the service control point. The first service-related query invokes at the control point a service logic program whose operation determines the instructions to be sent to the call control in order to provide a service.
Services offered by means of IN increase and become more and more versatile. A drawback with the above-described arrangement is that in feature interaction of various services, execution of another, simultaneous feature may be disturbed, since the services do not observe the difference in each other's features. Therefore, in some cases it would be advisable if a service detected in the originating half-call could be executed in the terminating half-call. In accordance with the prior art, this kind of a service cannot be invoked in the terminating half-call, since it is not possible to transfer sufficiently data from one half-call to another. These services are often related to services of the subscriber B. For instance, when number portability is implemented as an IN service in the mobile systems, problems arise with other IN service features, e.g. those developed for mobile telephone systems in accordance with CAMEL (Customised Applications for Mobile network Enhanced Logic) IN standard service facilities. The number portability means that the subscriber can change the operator and yet keep the old telephone number. In the present application the subscriber who has changed the operator but kept the old number is referred to as a ported subscriber.
There are situations, when it would be advisable for improved quality of service if the service logic, or a portion of it, which is normally invoked in the originating call model, is invoked on the terminating side. However, in the above-described arrangement this does not succeed, since the terminating call model is only related to the services of the subscriber B.